So let me give you a bit of my background...
I am 16 and going full fledge this year with landscaping.
In the last couple years I just put mark's landscaping which sounded more like a younger guy doing lawns. I would like to have a "name", that I can put on some business cards and a website, that does not look childish. On the same note, some people would rather hire a "kid" than a real company. I want to act and be treated like a professional, but I think I should hint that I am a student who is doing this on the side. As of now, I have 3 large weekly accounts. I am hoping to have about 5-6. Not sure how much I can manage with school and work.

Yeah, lots of rambeling... So to recap,
-hint that i'm a minor?
-help to think of a name

i think you should just stay with your name that you got, Mark's Landscaping.

there is nothing childish or even remotely wrong with that name and if you decide to stay at it and get bigger down the road the name will grow with you.

if you had some type of student themed name it would not work too well when you were no longer a student.

even if it something you are only doing until you are done with school you can still build up a nice client base and have something of value to sell.

i grew up with a guy that built up a nice little maintenence business with his family in his neihborhood when he was in high school and by the time he graduated he had 100 accounts and was doing very well.
the only thing he did which worked out great when he was smaller and in school but seemed to sound sillier over time was his name.

his business name was " Small, That's All " and people ate up the young kid trying to make a buck. now the dude has 8 -3 man crews going out every day and has 2 construction crews going out everyday as well as he does just about everything now and he even recently started getting into house flipping.

the money he makes is obcene and he built a great money making business but his name now seems so odd, the guy employs 30+ people and he is not so small anymore, in fact he is simply huge.

My thought is NO.
Your age should mean nothing its your work there interested in.
Put together a nice portfolio of the jobs you have done and have at it.
I don't go around saying "Hey hire me I'm 50 and smarter then a 16 year old"
You shouldn't shout "Hey I`m 16 and don`t now what I`m doing"
Be confident and truthful and you shouldn't have a problem.

Who gives a crap about your age? I see it all the time "I started a business and I'm only 13!" Well, WHOOP-DE-FLIPPIN-DOOO! It affords you JACK SQUAT. Then by age 14 they're shacking up with their 2 pregnant hoodrats collecting public assistance and living in a VAN DOWN BY THE RIVER!!!!!!!!

Am I wrong in thinking that you can't just "pick a name" for a business without registering it?

I mean, aside from a last name.

Even "Mark's" would need to be registered with the state - at least here it would.

Maybe we're just going on the "he's a kid, so it's OK to operate illegally" premise...
I know that sounds like I'm being a prick, but having a business card with some random name does not equate to operating a business.

Also, to address the question, I wouldn't indicate your age. As mentioned, people will simply assume you'll work for nothing. (Because that's what many young/college kids DO and it makes it tough on the rest of us)

The people who like that you are young are thinking you will work for next to nothing

I can condfidently tell you that if somebody once that lawn cut for 15-20$, I will never do that. The lawns that I have mostly 2 acres. I will admit I charge less than everyone else because I only look to make 19-20 an hour.

Am I wrong in thinking that you can't just "pick a name" for a business without registering it?

I mean, aside from a last name.

Even "Mark's" would need to be registered with the state - at least here it would.

Maybe we're just going on the "he's a kid, so it's OK to operate illegally" premise...
I know that sounds like I'm being a prick, but having a business card with some random name does not equate to operating a business.

Also, to address the question, I wouldn't indicate your age. As mentioned, people will simply assume you'll work for nothing. (Because that's what many young/college kids DO and it makes it tough on the rest of us)

I see your point. But, how am I, 16 year minor supposed to register a business and obtain insurance?, If it were easier to get insurance, I would.

I am not too far from Philly, but it sounds like it's rather strict in Pittsburgh.